2x2+5=8x2-211

Solution for 2x2+5=8x2-211 equation:

2x^2+5=8x^2-211

We move all terms to the left:

2x^2+5-(8x^2-211)=0

We get rid of parentheses

2x^2-8x^2+211+5=0

We add all the numbers together, and all the variables

-6x^2+216=0

a = -6; b = 0; c = +216;
Δ = b2-4ac
Δ = 02-4·(-6)·216
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-72}{2*-6}=\frac{-72}{-12}
=+6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+72}{2*-6}=\frac{72}{-12}
=-6
$